Jaguar Forum banner

Flat spots in acceleration (below 2.5k rpm) when cold?!

5K views 39 replies 7 participants last post by  hamedhbb 
#1 ·
Hi guys, long time lurker - first time posting.

move recently bought a 2010 xf-s portfolio with 86k miles and I’m thrilled with it so far.

everything seems to be in good order but I have noticed that during the first minute or so from a cold start the acceleration upto 2.5k rpm has a few flat spots. This seems to clear itself but I still feel a hesitation when the secondary turbo kicks in.

I have no eml’s on, no strange noises. Is this common on the 3.0d engine?

would appreciate to hear if you’ve experienced this and if it’s anything to worry about.

thanks.
 
#2 ·
Hi Lomond (live near Loch Lomond perchance?). Welcome to the forum.
I had a 2010 XF-S for 5 years but don't remember such flat spots. But if you are definitely linking it with the opening of the secondary turbo, there is a well-known and well-documented issue with the secondary turbo valve actuator - a small vacuum actuator that is a relatively inexpensive replacement/fix. It may be this starting to stick.
But first check some of the simple things like the air filter (is it dirty?), the induction pipework for loose connections or cracks. And it's quite an easy job to clean the two MAF sensors (one in each of the ducts coming off the LHS of the filter box.)
 
  • Like
Reactions: Lomond
#4 ·
Thanks for the reply. My next job (time permitting) was going to be replacing the throttle to intake manifold gaskets so I had planned on cleaning and perhaps swapping the MAF sensors.

had a quick look at the pipe work but I’m feeling a little daunted just looking at the 3.0l lump. I know my way around an engine but I’ve not much experience on things this complex/cramped.

car is running well after the initial start up so not too concerned. I maybe have read too many threads on this forum for my own good!
 
#3 ·
Welcome Lomond,

I also had a MY2010 XF-S, like yours with UB paint and volan alloys. Like John however, it never had any engine problems with flat spots. A fantastic car that is still missed, hope it gives you many happy motoring miles, once you get it sorted. Does sound like a possible sticking actuator on the secondary turbo though.

Oh, a picture or two is always good :)
 
#6 ·
Finally had the chance to do some digging...

cleaned the MAF sensors, the bottom sensor was obviously dirty so did my best to clean it and swapped it with the cleaner top one (Which was spotless) - this seems to have solved the hesitation between 2-3,000 rpm!

I also renewed the two gaskets between the throttle body and valve covers but doubt this would do much.


also I had a look at the compressor shut off valve and it was gleaming with no signs of dirt/oil anywhere on the actuator arm so I just left it as is.

wrt the dirty MAF - I’ve ordered a 2nd hand job from eBay so will swap it out for this as an experiment. As I say the car seems to be much smoother after the work I’ve done 👌
181773
 
#10 ·
After replacing the bottom MAF sensor, replacing the two circular gaskets that join the throttle body to the cam covers and cleaning the MAP sensor the flat spot is barely noticeable. Unsure which made the most difference but the MAF I replaced was badly soiled.I was unsure how hard to go cleaning the MAP so I just cleaned the outermost ring with a cloth and sprayed plenty of contact cleaner into the hole.

had a look at CSOV but it looked spotless so didn’t pull it. Next chance I get I will remove it to inspect properly.
 
#22 ·
It will remain a mystery for now. The car runs well as it is (it’s just my ocd that notices these slight problems). It’ll either remain the same or get worse and if that happens at least I’ll maybe have more of a clue as to what the problem actually is.

leaning towards primary turbo or injector fault.

thanks for the input guys and I’ll keep you posted.
 
#23 ·
In my industry we occasionally get 'slight' problems, they are a pain!!

Never quite enough evidence to formulate a plan.. it's much better when things have the decency to fail properly... (y)
 
  • Like
Reactions: FCS and hamedhbb
#32 ·
Cleaned the butterfly valve in the throttle body today and fitted a new o ring on the front of the throttle body.

no change I’m afraid.

I have noticed some oil misting on the left side egr hose (orange one) and looks to be a slight leak from either that pipe or the intake pipe to the turbo. It’s very slight so not sure if this could be a contributing factor?
 
#39 ·
Thanks for driving that out Hamed, I really appreciate the time you’ve taken to try and help me out.
But after using a bottle of turbo cleaner and using branded diesel (and everything else Ive done) the problem has disappeared. This leads me to think that it was a problem with the actuator on the primary turbo.
Either that it’s something completely different 😂.

thanks again,

alan.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top